(a) Field of the Invention
The present invention relates to an improved dry cleaning machine for use in dry cleaning establishments and similar industries.
More particularly, the present invention relates to a dry cleaning machine that incorporates a solvent filtration unit using a new kind of micro-filtration filter and/or a solvent regeneration unit for use to reactivate the carbon powder used to keep the laundry cleaning solvent colorless from batch to batch.
( b) Brief Description of the Prior Art
Dry cleaning machines are machines that are well known per se and used almost everywhere throughout the world. These machines usually comprise a rotating drum in which the laundry to be cleaned is introduced. An organic solvent such as perchloroethylene is injected into the drum while the same is rotating to clean the laundry. This solvent is usually kept into a tank and fed into the drum by means of a pump connected to the tank.
Of course, the solvent also has to be cleaned up from time to time. To do so, most of the dry cleaning machines presently available on the market include means for regenerating and purifying the solvent, such means usually comprising:
(a) a lint collector mounted in-line in the solvent feed line downstream the pump to catch any big particles that could be drained out of the drum during the cleaning operation; PA1 (b) a solvent filtration unit including at least one filter through which the solvent may be passed downstream the lint collector to remove therefrom smaller particles; PA1 (c) a solvent decoloration unit including an activated carbon tower through which the solvent may also be passed whenever necessary (e.g. when the solvent is so "loaded" that it becomes colored); and PA1 (d) a solvent distillation unit comprising a still, a condenser and a separator through which part of the solvent may be processed to remove any organic impurities contained therein prior to re-using it for cleaning the garment in the drum. PA1 a rotating drum in which the laundry to be cleaned is treated with a cleaning solvent, said drum having a solvent inlet and a solvent outlet; PA1 at least one storage tank for the solvent, this tank having a solvent inlet and a solvent outlet; PA1 a solvent feed line extending from the outlet of the storage tank to the inlet of the drum, the feed line including a lint collector; PA1 a pump for circulating the solvent from the tank to the drum through the feed line; PA1 a solvent return line extending from the outlet of the drum to the inlet of the storage tank, this return line including a button trap, PA1 a solvent filtration unit including at least one filter and means for allowing at least part of the solvent circulating through the feed line downstream the lint collector to pass through this filter to block any mechanical impurities; PA1 a solvent decoloration unit that may be combined with the filtration unit and includes a bed of activated carbon and means for allowing at least part of the solvent having passed through the filter to pass through the carbon bed; PA1 a solvent distillation unit including a still, a condenser, a separator and means for allowing at least part of the solvent having passed through at least the lint collector to be fed into the still and distilled therein, then condensed in the condenser and finally returned to the storage tank via the separator and a return pipe; and PA1 a regeneration unit to reactivate the carbon used in the decoloration unit whenever necessary, this regeneration unit comprising: PA1 a chamber in which the carbon to be reactivated is introduced and processed; PA1 means such as a steam jacket for heating the chamber to evaporate the solvent dripping from the carbon to be reactivated and subsequently drying this carbon after the regeneration process has been completed; PA1 means for injecting live steam into the heated chamber to desorb the carbon to be reactivated; and PA1 piping means to direct the evaporated solvent and desorbsion steam from the heated chamber to the still of the solvent distillation unit. PA1 a rotating drum in which the laundry to be cleaned is treated with a cleaning solvent, said drum having a solvent inlet and a solvent outlet; PA1 at least one storage tank for the solvent, said at least one tank having a solvent inlet and a solvent outlet; PA1 a solvent feed line extending from the outlet of said at least one storage tank to the inlet of the drum, said feed line including a lint collector; PA1 a pump for circulating the solvent from said at least one tank to the drum through the feed line; PA1 a solvent return line extending from the outlet of the drum to the inlet of said at least one storage tank, said return line including a button trap, PA1 a solvent filtration unit including at least one filter and means for allowing at least part of the solvent circulating through the feed line downstream the lint collector to pass through said at least one filter. In this embodiment, the filtration unit comprises two filters mounted in line and each consisting of a bag made of fabric and wherein the upstream filter has a mesh of about 10 to 25 microns and the downstream filter has a mesh of 1 to 10 microns. Preferably, the lint collector consists of a Nylon bag having a mesh of 50 to 75 microns; PA1 the bag forming the upstream filter of the filtration unit is made of Nylon; and PA1 the bag forming the downstream filter of the filtration unit is made of a composite fabric having a multi-layered cell structure that swells when the solvent is passing therethrough.
In the filtration and decoloration units, use has been made up to now of powder filters and/or cartridges that must be replaced from time to time.
The powder filters presently available on the market consist of diatomaceous earth deposited on screens, nylon discs or wovened tubes to form a filtering cake. For decoloration purpose, carbon powder may be added to this basic structure. The major problem of such filters lies in that they are mechanically complicated and dirty. As a result, trained operators are needed to change them and a lot of hazardous waste is generated because of the powder and carbon they contain. As a matter of fact, in use, approximately 1 pound of dirt from the filter(s) may clog the solvent per 100 pounds of garment being processed.
The cartridges are much more convenient than the powder filter. Accordingly, they are in greater use today (they represent 85% of the solvent purification systems presently used in the industry). Their major drawback however is their cost of purchasing and their cost of disposal as a substantial amount of solvent is always trapped into the cartridges and thus disposed therewith.